The fluidized catalytic cracking (FCC) of heavy hydrocarbons to produce lower boiling hydrocarbon products such as gasoline is well known in the art. FCC processes have been around since the 1940's. Typically, an FCC unit or process includes a riser reactor, a catalyst separator and stripper, and a regenerator. A FCC feedstock is introduced into the riser reactor wherein it is contacted with hot FCC catalyst from the regenerator. The mixture of the feedstock and FCC catalyst passes through the riser reactor and into the catalyst separator wherein the cracked product is separated from the FCC catalyst. The separated cracked product passes from the catalyst separator to a downstream separation system and the separated catalyst passes to the regenerator where the coke deposited on the FCC catalyst during the cracking reaction is burned off the catalyst to provide a regenerated catalyst. The resulting regenerated catalyst is used as the aforementioned hot FCC catalyst and is mixed with the FCC feedstock that is introduced into the riser reactor.
Many FCC processes and systems are designed so as to provide for a high conversion of the FCC feedstock to products having boiling temperatures in the gasoline boiling range. There are situations, however, when it is desirable to provide for the high conversion of the FCC feedstock to middle distillate boiling range products, as opposed to gasoline boiling range products, and to lower olefins. However, making lower olefins requires high severity and high reaction temperature reaction conditions. These conditions normally result in low middle distillate product yield and poor middle distillate product quality. It is therefore very difficult in the conventional cracking of hydrocarbons to provide simultaneously for both a high yield of lower olefins and a high yield of middle distillate products.
United States Patent Application Publication 2006/0178546 discloses a process for making middle distillate and lower olefins. The process includes catalytically cracking a gas oil feedstock within a riser reactor zone by contacting under suitable catalytic cracking conditions within the riser reactor zone the gas oil feedstock with a middle distillate selective cracking catalyst that comprises amorphous silica alumina and a zeolite to yield a cracked gas oil product and a spent cracking catalyst. The spent cracking catalyst is regenerated to yield a regenerated cracking catalyst. Within an intermediate cracking reactor such as a dense bed reactor zone and under suitable high severity cracking conditions a gasoline feedstock is contacted with the regenerated cracking catalyst to yield a cracked gasoline product and a used regenerated cracking catalyst. The used regenerated cracking catalyst is utilized as the middle distillate selective catalyst. United States Patent Application Publication 2006/0178546 is herein incorporated by reference in its entirety.
United States Patent Application Publication 2006/0178546 allows the use of a used regenerated cracking catalyst from an intermediate cracking reactor to be used as a middle distillate selective catalyst in a riser reactor zone.
There is a need in the art to provide for the use of renewable resources.
There is a further need in the art to replace petroleum feedstocks with plant and/or animal derived feedstocks.
There is a further need in the art to increase conversion of plant and/or animal derived feedstocks to middle distillate boiling range products and to lower olefins.
There is a further need in the art to simultaneously produce middle distillate and lower olefin products from a plant and/or animal derived feedstock.